Magnetically Preloaded Anti-Rotation Guide for a Transducer

ABSTRACT

A transducer positioning apparatus is provided that supports a read/write head on a data storage machine and biases the head against rotation. The transducer positioning apparatus may comprise a base that includes a linear drive motor and a support frame to which the read/write head is secured. The support frame is reciprocally driven by the linear drive motor relative to the base. A magnetic coupling is provided between the base and the support frame that resists movement of the frame other than the reciprocal movement of the support frame relative to the base. A method is also disclosed for magnetically biasing a movable head of a transducer against rotation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an anti-rotation guide for a media drivetransducer.

2. Background Art

Anti-rotation guides for transducers are used in media drives to inhibitrotational movement of a transducer when the direction of tape movementis reversed with respect to a tape head. Examples of transducerpositioning devices are disclosed in U.S. Pat. Nos. 6,437,946 and6,985,430.

Anti-rotation guides for transducers are generally preloaded to removeplay and minimize undesirable head movements. The most common method ofpreloading is to use springs that bias the anti-rotation guides. Springpreloading mechanisms may be a source of reliability and performanceissues. Reliability and performance problems may arise due to componentfatigue, component wear, and unpredictable frictional forces that mayoccur at preload component interfaces. Such reliability and performanceproblems may contribute to poor actuator performance and reducedanti-rotation guide and head actuator product life.

Anti-rotation guide spring preload mechanisms are small parts ofconsiderable complexity. The cost of assembling such small, complexparts increases the cost of assembling the anti-rotation guides and headactuator assemblies.

The present invention is directed to overcoming the above problems assummarized below.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a transducerpositioning apparatus is provided that supports a read/write head on adata storage machine. One embodiment of the transducer positioningapparatus comprises a base that includes a linear drive motor. Thetransducer positioning apparatus also has a support frame to which theread/write head is secured. The support frame is reciprocally driven bythe linear drive motor relative to the base. A magnetic coupling isprovided between the base and the support frame that resists movement ofthe frame other than the reciprocal movement of the support framerelative to the base.

According to another aspect of the invention, the magnetic coupling ofthe transducer positioning apparatus includes a magnet having a magneticflux field. A ball and a magnetically attracted member are both disposedin the magnetic flux field. The magnetic flux field captures the ballbetween the magnet and the magnetically attracted member whilepermitting the magnet and the member to move relative to each otherlinearly with the ball rolling therebetween.

According to still further aspects of the invention, the magnet may beprovided on the base with the magnetically attracted member beingprovided on the frame. Alternatively, the magnet may be provided on theframe with the magnetically attracted member being provided on the base.In either case, the magnetically attracted member may be a magnet.

According to the another aspect of the invention, an anti-rotation guideis provided for a transducer positioning apparatus of a data storagemachine. The anti-rotation guide has a base and a tower extending fromthe base. A frame is attached to the tower. A transducer head reads andwrites data to a storage medium, such as a data storage tape. Thetransducer head is secured to the frame for limited movement along thetower and toward and away from the base. The transducer head ispivotable to a limited extent relative to the tower about a pivot axiswhen the storage medium reverses direction. The anti-rotation guidecomprises a magnetically attracted portion of the frame that is radiallyspaced from the pivot axis. A ball is disposed near the magneticallyattracted portion of the frame. A magnet attached to the tower acts upona magnetically attracted portion of the frame to bias the transducerhead against rotation about the pivot axis when the storage mediumreverses direction. The head rolls on the ball relative to themagnetically attracted portion.

According to other aspects of the invention as it relates to theanti-rotation guide, the ball may be disposed between the magneticallyattracted portion of the frame and the magnet. The transducer head rollson the ball as the head moves toward and away from the base. Theanti-rotation guide may further comprise a linear guide track thatguides the movement of the frame relative to the tower. The linear guidetrack may be split into two portions with the first portion beingdisposed above the magnetically attracted portion of the anti-rotationflange and a second portion being disposed below the magneticallyattracted portion of the anti-rotation flange. The tower may provide aslot between the first and second portions of the track in which themagnetically attracted portion of the anti-rotation flange is received.The anti-rotation guide may further comprise a ball disposed between themagnetically attracted portion of the anti-rotation flange and themagnet. The transducer head rolls on the ball as the head moves towardand away from the base. A wear plate may be disposed between the magnetand the ball.

Another aspect of the invention relates to a method of retaining amovable head of a transducer on a base. The transducer used in themethod includes a linear motor that operatively engages a frame thatsupports the head. The frame and the base define an anti-rotation guidefor the head. The anti-rotation guide may have a ball disposed between amagnetically attracted portion of the frame (for example, ananti-rotation flange) and a magnet disposed on the base. The methodcomprises providing a magnetic field that retains the ball in engagementbetween the magnetically attracted portion of the frame and the magnet.Movement of the tape is tracked in a direction perpendicular to thedirection of travel for the tape. A representative signal is provided toa controller that is representative of the movement of the tape in theperpendicular direction. The frame supporting the head is driven by thelinear motor in the linear direction in response to a signal from thecontroller that is based on the representative signal. Rotation of theframe relative to the base is resisted by the magnetic field when thetape changes direction.

According to another aspect of the method of present invention, themagnetically attracted portion of the frame may further comprise ananti-rotation flange extending away from the head that is received bythe base. The method further comprises the step of biasing the flangeagainst rotation relative to the head in the direction of travel of thetape.

These and other aspects of the present invention will be betterunderstood in view of the attached drawings and the following detaileddescription of the illustrated embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an outer perspective view of a head actuator;

FIG. 2 is a front exploded perspective view of the head actuator;

FIG. 3 is a rear exploded perspective view of the head actuator;

FIG. 4 is a top plan view of the head actuator;

FIG. 5 is a diagrammatic top plan view of an alternative embodiment of ahead actuator;

FIG. 6 is a diagrammatic top plan view of another alternative embodimentof a head actuator;

FIG. 7 is a side perspective view of an anti-rotation guide portion ofthe head actuator;

FIG. 8 is a diagrammatic top plan view of an alternative embodiment ofan anti-rotation guide portion of a head actuator; and

FIG. 9 is a diagrammatic top plan view of an alternative embodiment ofan anti-rotation guide portion of a head actuator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to FIG. 1, a transducer head positioning apparatus 10 isillustrated. The transducer head positioning apparatus 10 includes abase assembly 12 and a head assembly 14. The head assembly 14 issupported in part by a linear motion track 16 that is defined by boththe base assembly 12 and the head assembly 14. A magnetic couplingsystem is generally represented by reference numeral 18 that functionsin conjunction with the linear motion track 16 to guide the movement ofthe head assembly 14 relative to the base assembly 12. The head assembly14 is used to read and write data to a data storage tape 20 in theillustrated embodiment. However, it should be understood that theinvention is not limited to tape storage applications and could beadapted, for example, to disk storage applications.

The base assembly 12 includes a base 22 and a linear motor 24. Thelinear motor 24 has a plurality of legs 26 that operatively engage thehead assembly 14 to move the head assembly 14 in a linear directionreciprocally relative to the base 22. The base assembly 12 also includesa tower 28 that extends from the base 22.

The head assembly 14 includes a frame 30 that defines a head support 32.The frame 30 also includes a tripod support 34 that is connected to thethree legs 26 of the linear motor 24. A head 36 is attached to the headsupport 32. The head 36 is a read/write head which may also be referredto as a transducer head that is used to read and write data to a datastorage tape or other data storage medium.

Referring to FIGS. 2 and 3, the transducer head positioning apparatus 10is shown in oppositely oriented exploded perspective views. The linearmotion track generally referred to in FIG. 1 by reference numeral 16 isseparated into its component parts wherein a first upper movable track38 and a second upper movable track 40 are provided on the head assembly14. A first upper stationary track 42 and a second upper stationarytrack 44 are shown in a facing relationship relative to the first andsecond upper movable tracks 38 and 40. An upper ball 46 is restrainedbetween the movable tracks 38, 40 and the stationary tracks 42, 44.

First and second lower movable tracks 48, 50 are provided on the frame30 of the head assembly 14 at locations below the upper movable tracks38, 40, as viewed in FIG. 2. First and second lower stationary tracks52, 54 are provided below the first and second upper stationary tracks42, 44, as illustrated in FIGS. 2 and 3. A lower ball 56 is confinedwithin the movable tracks 48, 50 and the stationary tracks 52, 54.

The track 16 guides movement of the frame 30 in conjunction with thetower 28. The frame 30 is moved by the linear motor 24 that has legs 26that engage the tripod support 34 of the frame 30. The linear motor 24drives the legs 26 in a linear direction reciprocally in response tocontrol signals received from a controller (not shown).

The magnetic coupling system 18 is described by reference to FIG. 4. Thetransducer head positioning apparatus 10 includes the base assembly 12.The magnetic coupling system 18 retains the frame 30 of the headassembly 14. In the embodiment shown in FIG. 4, the magnetic couplingsystem 18 includes a first magnet 60 and a second magnet 62 thatcooperate with the first magnetically attracted member 64 and the secondmagnetically attracted member 66 to support the frame 30 on the upperball 46. A lower portion of the linear motion track 16 is not visible inFIG. 3, but is aligned with the upper portion of the linear motion track16. The oval line with arrowheads illustrates generally the magneticflux path of the magnetic coupling system 18. The magnetic flux pathholds the ball 46 and magnetically attracted members 64, 66 to themagnets 60, 62. The frame 30 is generally free to move along the linearmotion track 16 with upper ball 46 and lower ball 56 providing a rollingsupport for the frame 30 of the head assembly 14.

The legs 26 of the linear motor 24 engage the tripod support 34 of thehead assembly 14 to reciprocally drive the head assembly 14 to trackmovement of the data storage tape perpendicular to the direction ofmovement of the data storage tape. Base wear plates 70 and head wearplates 68 are shown on the first and second magnets 60, 62 and on thefirst and second magnetically attracted members 64, 66, respectively.The wear plates 68, 70 are made of hardened steel or ceramic and reducewear occurring as a result of the movement of the head assembly 14 as itrolls on the balls 46, 56.

Referring to FIG. 5, a dual magnet track embodiment 72 is shown. Thedual magnet track embodiment 72 includes head assembly magnets 74 andbase magnets 76 that are arranged to provide a flux path that retainsthe ball 46 within the linear motion track 16. Ball 46 shown in FIG. 4is the upper ball, while the lower ball 56 is maintained generally inalignment with the upper ball 46 in a similar arrangement. Wear plates78 are provided to provide a wear resistant surface upon which the ball46 may roll when the head assembly 14 is moved relative to the baseassembly 12.

Referring to FIG. 6, a further embodiment of the present inventionreferred to as the head assembly magnet embodiment 80 is shown toinclude a pair of head magnets 82 that are assembled to the frame 30.Magnetically attracted members 84 are provided on the base assembly 12.The magnetically attracted members 84 may be steel or other ferrousmaterial. Wear plates 86 may be provided in conjunction with or inaddition to the magnetically attracted members 84 and the head magnets82 to provide a wear surface over which the ball 46 may roll. A lowertrack may be provided that rolls on a ball 56 in like manner.

Referring to FIG. 7, an anti-rotation guide system 90 is shown inconjunction with the base assembly 12 and head assembly 14 that definethe linear motion track 16 as previously described. The anti-rotationguide system 90 may be used in conjunction with the linear motion track16 having a magnetic coupling system 18, as previously described withreference to FIGS. 1-5. The anti-rotation guide system 90 includes amagnet 92 and a ball 94 that cooperate with an anti-rotation flange 96of the frame 30. The anti-rotation flange 96 extends through a slot 98formed in the tower 28 of the base assembly 12. The oval line witharrowheads that passes through the magnet 92, ball 94 and anti-rotationflange 96 is provided to indicate the flux path of the anti-rotationguide system 90. The magnet 92 exerts a biasing force through themagnetic flux field that biases the anti-rotation flange 96 intoengagement with the ball 94. A wear plate 100 may be provided on themagnet 92. Another wear plate 102 may be provided on the anti-rotationflange 96. The wear plate may be made of ferrous or ceramic material andmay form part of the magnetic coupling system that couples theanti-rotation flange 96 to the magnet 92. The anti-rotation flange 96may be moved when the linear motor moves the legs 26 to move the headassembly 14 as it tracks the data storage tape. When the frame 30 of thehead assembly 14 moves up and down, as shown in FIG. 6, theanti-rotation flange 96 rolls the ball 94 between the wear plate 100 onthe magnet 92 and wear plate 102 on the flange 96.

Referring to FIG. 8, a dual magnet anti-rotation system 110 is shown toinclude a magnet 112 that is attached to the base assembly 12 and amagnet 114 that is attached to the frame 30. A magnetic flux path isillustrated by the elliptical line with arrowheads that extends from themagnet 112 to the magnet 114 and through the ball 118. The magnets 112,114 retain the ball 118 between the anti-rotation flange 116 and thebase 12. Wear plates 120, as previously described, are provided forengagement with the ball 118 to reduce wear on the component parts ofthe dual magnet anti-rotation system 110 when the frame 30 rolls on theball 118 relative to the base assembly 12. Wear plates 120 may also beincluded in the flux path if made of ferrous material.

Referring to FIG. 9, a magnet anti-rotation system 124 is shown toinclude a magnet 126 that is attached to the frame 30 of the headassembly 14. A magnetic flux path is illustrated by the elliptical linewith arrowheads that extend from the magnet 126 through the wear plates120 and through the ball 128. The wear plate 120 on the base 12, if madeof a ferrous material, may function as the magnetically attractedportion of the base 12. The magnet 126 retains the ball 128 between theanti-rotation flange 116 and the base 12. Wear plates 120, as previouslydescribed, are provided for engagement with the ball 128 to reduce wearon the component parts of the anti-rotation system 124 when the frame 30rolls on the ball 128 relative to the assembly 12.

While embodiments of the invention have been illustrated and described,it is not intended that these embodiments illustrate and describe allpossible forms of the invention. Rather, the words used in thespecification are words of description rather than limitation, and it isunderstood that various changes may be made without departing from thespirit and scope of the invention.

1. A transducer positioning apparatus that supports a read/write head ofa data storage machine, the transducer positioning apparatus comprising:a base that includes a linear drive motor; a support frame to which theread/write head is secured, the support frame is reciprocally driven bythe linear drive motor relative to the base; and a magnetic couplingbetween the base and the support frame that resists movement of theframe other than the reciprocal movement of the support frame relativeto the base.
 2. The transducer positioning apparatus of claim 1 whereinthe magnetic coupling comprises: a magnet having a magnetic flux field;a ball disposed in the magnetic flux field; and a magnetically attractedmember disposed in the magnetic flux field that captures the ballbetween the magnet and the member while permitting the magnet and themember to move relative to each other in a line with the ball rollingtherebetween.
 3. An anti-rotation guide apparatus for a transducerpositioning apparatus of a data storage machine that reads and writesdata to a storage medium, a base, a tower extending from the base at oneend, a transducer head for reading and writing data to a storage mediumthat is secured to a frame, the frame is movably attached to the towerfor limited movement toward and away from the base, the transducer headis pivotable with the frame to limited extent with the frame relative tothe tower about a pivot axis when the storage medium reverses direction,the anti-rotation guide apparatus comprising; an anti-rotation flange ofthe frame that is radially spaced from the pivot axis; a ball disposedproximate the anti-rotation flange of the frame; a magnet attached tothe projection that acts upon the anti-rotation flange of the frame tobias the transducer head against rotation about the pivot axis when thestorage medium reverses direction, wherein the frame rolls on the ballrelative to the magnetically attracted portion.
 4. The apparatus ofclaim 3 wherein the ball is disposed between the anti-rotation flange ofthe frame and the magnet, wherein the frame rolls on the ball bearing asthe head moves toward and away from the base.
 5. The apparatus of claim3 further comprising a linear guide track that guides the movement ofthe head relative to the base.
 6. The apparatus of claim 5 wherein thelinear guide track is split into two portions, wherein a first portionis disposed above the anti-rotation flange of the frame and a secondportion is disposed below the anti-rotation flange of the frame.
 7. Theapparatus of claim 6 wherein the projection defines a slot between thefirst and second portions of the track and wherein the anti-rotationflange of the frame is received in the slot.
 8. The apparatus of claim 3wherein the storage medium is a data storage tape.
 9. The apparatus ofclaim 3 further comprising further comprising a ball disposed betweenthe anti-rotation flange of the frame and the magnet, wherein the framerolls on the ball bearing as the head moves toward and away from thebase, and a wear plate is disposed between the magnet and the ballbearing.
 10. A method of retaining a movable head assembly of atransducer on a base of the transducer, the transducer further includinga linear motor in the base that operatively engages a frame of the headassembly, the movable head assembly and base defining an anti-rotationguide for the transducer; the anti-rotation guide having a ball disposedbetween a magnetically attracted portion of the frame and a magnetdisposed on the base, the method comprising: providing a magnetic fieldthat retains the ball in engagement between the magnetically attractedportion of the frame and the magnet; tracking the movement of a tape ina direction perpendicular to the direction of travel of the tape;providing a representative signal to a controller that is representativeof the movement of the tape in the perpendicular direction; driving thehead assembly with the linear motor in the perpendicular direction inresponse to a signal from the controller that is based upon therepresentative signal; and resisting rotation of the head assemblyrelative to the base with the magnetic field when the tape changesdirection.
 11. The method of claim 10 wherein the magnetically attractedportion of the frame further comprises an anti-rotation flange extendingaway from the head that is received by the base, and wherein the methodfurther comprises the step of biasing the flange against rotationrelative to the head in the direction of travel of the tape.
 12. Themethod of claim 10 further comprising rolling the frame on the ballduring the step of driving the head assembly in the perpendiculardirection.